The present disclosure relates to a method of controlling auto exposure of a digital camera, and more particularly, to a method of controlling adaptive auto exposure to emphasize an object by: dividing a digital photograph captured from an object and a background into an object region where the object is mainly located and a background region where the background is mainly located; calculating average luminances of the object and background regions; calculating a luminance difference between the average luminances of the object and background regions; calculating an average luminance of the entire photograph by applying a weight to the average luminance of the object region if the luminance difference is within a predetermined range, and controlling exposure based on the calculated average luminance of the entire photograph.
Improper exposure to light is one of important factors that affect image quality and result in poor-quality photographs. Although new features such as auto gain control algorism are added to recent cameras, such limitation cannot be completely removed.
Therefore are various methods for controlling exposure of digital cameras. However, such methods are not optimal, and thus images may be captured under improper exposure conditions. Particularly, handset devices such as cellular phones may be serious in this limitation. That is, images taken by using such handset devices have poor quality due to improper exposure caused by poor-quality optical devices, no-flash conditions, and no use of precise light adjusting devices.
It may be difficult to determine proper exposure. However, if general conditions are reviewed and the most important region is mainly considered, it may be possible to define optimal exposure based on central values of gray or luminance levels of regions according to situations or perceptions. In any cases, if a dynamic region of a scene is perceptually high, it may be generally difficult to obtain detail information.
Many auto exposure (AE) algorisms have been developed. However, such auto exposure algorisms are inaccurate or complex.